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Glucosamine and chondroitin sulfate are natural substances found in healthy cartilage. Glucosamine is an amino sugar. Chondroitin sulfate is a complex carbohydrate that helps cartilage retain water.

Glucosamine and chondroitin are sold as dietary supplements in the U.S. Their effectiveness in improving cartilage health is controversial among physicians.

"The clinical studies have been mixed, with some showing small to modest effects and others showing no effect," said Constance Chu, director of the Cartilage Restoration Center at UPMC.

The studies that show a positive effect involved concentrations of chondroitin sulfate much higher than what typically is taken orally, Dr. Chu said.

"Three studies showed [glucosamine and chondroitin] to be no better than a placebo," said Nicholas Sotereanos, director of the Center for Restorative Joint Surgery at Allegheny General Hospital. "One study at Johns Hopkins showed some effectiveness, but the study was funded by a pharmaceutical company. For me in my practice, this is voodoo."

The results of a clinical trial published in September indicated chondroitin sulfate significantly decreased pain and improved hand function in patients with osteoarthritis of the hand.

In the trial, funded by the Institut Biochemique SA, a Swiss pharmaceutical company, and conducted by physicians affiliated with the University of Geneva, 80 patients received 800 milligrams of chondroitin sulfate and 82 patients received a placebo once daily for six months.

Pain relief was measured on the 100-point visual analogue scale. The chondroitin recipients reported an average decline of 8.7 points.

Hand function was measured on the 30-point Functional Index for Hand OA. The chondroitin recipients improved hand function by 2 points on that index.

"The effect of [chondroitin sulfate] on the function seemed more pronounced than the effect on global hand pain," said the study, which was published in the September issue of Arthritis and Rheumatism, the journal of the American College of Rheumatology.

The chondroitin takers also reported a significant reduction in morning stiffness.

The study was restricted to patients with severe hand arthritis, and the researchers did not collect data on the effect of chondroitin on other joints such as the knee.

In another study, a steroid drug currently used to treat inflammatory diseases could also prevent osteoarthritis from developing in people who suffer knee injuries, if given soon after injury.

Massachusetts Institute of Technology researchers tested the effects of glucocorticoids, steroids that can help reduce swelling and pain in arthritic joints. They've been prescribed for decades to treat chronic rheumatoid arthritis in the elderly.

The researchers found that when damaged bovine cartilage tissue is treated immediately with the glucocorticoid dexamethasone, cartilage breakdown caused by inflammatory proteins called cytokines -- typically released after a joint injury -- is halted. The drug works up to two days after the injury, the researchers found.

The researchers aren't sure why dexamethasone works. But they found evidence it blocks degradation of aggrecan, a protein-carbohydrate complex that is a major functional component of cartilage. They plan to investigate this in future studies and to try to determine if dexamethasone can go beyond halting cartilage damage to actually repairing it. They said they will also explore the best means of delivering dexamethasone to injured joints.

But first, the researchers plan more animal studies to determine how many treatments are required to maintain dexamethasone's protective effect. If these studies have positive results, the drug could be used to treat people with injured knees soon after, because dexamethasone already is approved by the FDA for use by humans, said Alan Grodzinsky, director of MIT's Center for Biomedical Engineering and the lead author of the study.

The study was published Sept. 2 in the journal Arthritis Research and Therapy.